Search

Tumor Profiler Consortium author list

Table ST5: Table of the 15 most informative proteins upregulated in MEK inhibitor-resistant cell culture (ranked by log2 fold-change).

S13: Immunohistochemical analysis of CyTof biomarker panel.

S16: scRNA-sequencing analysis of xenograft tumors M130227

Clinical management of melanomas with NRAS mutations is challenging. Targeting MAPK signaling is only beneficial to a small subset of patients due to resistance that arises through genetic, transcriptional, and metabolic adaptation. Identification of targetable vulnerabilities in NRAS-mutated melanoma could help improve patient treatment. Here, we used multiomics analyses to reveal that NRAS-mutated melanoma cells adopt a mesenchymal phenotype with a quiescent metabolic program to resist cellular stress induced by MEK inhibition. The metabolic alterations elevated baseline reactive oxygen species (ROS) levels, leading these cells to become highly sensitive to ROS induction. In vivo xenograft experiments and single-cell RNA sequencing demonstrated that intratumor heterogeneity necessitates the combination of a ROS inducer and a MEK inhibitor to inhibit both tumor growth and metastasis. Ex vivo pharmacoscopy of 62 human metastatic melanomas confirmed that MEK inhibitor–resistant tumors significantly benefited from the combination therapy. Finally, oxidative stress response and translational suppression corresponded with ROS-inducer sensitivity in 486 cancer cell lines, independent of cancer type. These findings link transcriptional plasticity to a metabolic phenotype that can be inhibited by ROS inducers in melanoma and other cancers.Significance:Metabolic reprogramming in drug-resistant NRAS-mutated melanoma cells confers sensitivity to ROS induction, which suppresses tumor growth and metastasis in combination with MAPK pathway inhibitors.

Impaired proinsulin-to-insulin processing in pancreatic β-cells is a key defective step in both type 1 diabetes and type 2 diabetes (T2D) (refs. 1,2), but the mechanisms involved remain to be defined. Altered metabolism of sphingolipids (SLs) has been linked to development of obesity, type 1 diabetes and T2D (refs. 3–8); nonetheless, the role of specific SL species in β-cell function and demise is unclear. Here we define the lipid signature of T2D-associated β-cell failure, including an imbalance of specific very-long-chain SLs and long-chain SLs. β-cell-specific ablation of CerS2, the enzyme necessary for generation of very-long-chain SLs, selectively reduces insulin content, impairs insulin secretion and disturbs systemic glucose tolerance in multiple complementary models. In contrast, ablation of long-chain-SL-synthesizing enzymes has no effect on insulin content. By quantitatively defining the SL–protein interactome, we reveal that CerS2 ablation affects SL binding to several endoplasmic reticulum–Golgi transport proteins, including Tmed2, which we define as an endogenous regulator of the essential proinsulin processing enzyme Pcsk1. Our study uncovers roles for specific SL subtypes and SL-binding proteins in β-cell function and T2D-associated β-cell failure.

Aims: Therapeutic modulation of blood vessel growth holds promise for the prevention of limb ischemia in diabetic (DM) patients with peripheral artery disease (PAD). Epigenetic changes, namely posttranslational histone modifications, participate in angiogenic response suggesting that chromatin-modifying drugs could be beneficial in this setting. Apabetalone (APA), a selective inhibitor of bromodomain (BRD) and extra-terminal (BET) proteins, prevents BRD4 interactions with chromatin thus modulating transcriptional programs in different organs. We sought to investigate whether APA affects angiogenic response in diabetes.Results: As compared to vehicle, APA restored tube formation and migration in human aortic endothelial cells (HAECs) exposed to high glucose (HG) levels. Expression profiling of angiogenesis genes showed that APA prevents HG-induced upregulation of the anti-angiogenic molecule Thrombospondin-1 (THBS1). ChIP-seq and chromatin immunoprecipitation (ChIP) assays in HG-treated HAECs showed the enrichment of both BRD4 and active marks (H3K27ac) on THBS1 promoter, whereas BRD4 inhibition by APA prevented chromatin accessibility and THBS1 transcription. Mechanistically, we show that THBS1 inhibits angiogenesis by suppressing VEGFA signaling, while APA prevents these detrimental changes. In diabetic mice with hindlimb ischemia, epigenetic editing by APA restored THSB1/VEGFA axis thus improving limb vascularization and perfusion as compared to vehicle-treated animals. Finally, epigenetic regulation of THSB1 by BRD4/H3K27ac was also reported in DM patients with PAD as compared to non-diabetic controls.Innovation: This is the first study showing that BET protein inhibition by APA restores angiogenic response in experimental diabetes.Conclusions: Our findings set the stage for preclinical studies and exploratory clinical trials testing APA in diabetic PAD.

Therapeutic modulation of blood vessel growth holds promise for the prevention of limb ischemia in diabetic (DM) patients with peripheral artery disease (PAD). Epigenetic changes, namely posttranslational histone modifications, participate in angiogenic response suggesting that chromatin-modifying drugs could be beneficial in this setting. Apabetalone (APA), a selective inhibitor of bromodomain (BRD) and extra-terminal (BET) proteins, prevents BRD4 interactions with chromatin thus modulating transcriptional programs in different organs. We sought to investigate whether APA affects angiogenic response in diabetes. Results:As compared to vehicle, APA restored tube formation and migration in human aortic endothelial cells (HAECs) exposed to high glucose (HG) levels. Expression profiling of angiogenesis genes showed that APA prevents HG-induced upregulation of the anti-angiogenic molecule Thrombospondin-1 (THBS1). ChIP-seq and chromatin immunoprecipitation (ChIP) assays in HG-treated HAECs showed the enrichment of both BRD4 and active marks (H3K27ac) on THBS1 promoter, whereas BRD4 inhibition by APA prevented chromatin accessibility and THBS1 transcription. Mechanistically, we show that THBS1 inhibits angiogenesis by suppressing VEGFA signaling, while APA prevents these detrimental changes. In diabetic mice with hindlimb ischemia, epigenetic editing by APA restored THSB1/VEGFA axis thus improving limb vascularization and perfusion as compared to vehicle-treated animals. Finally, epigenetic regulation of THSB1 by BRD4/H3K27ac was also reported in DM patients with PAD as compared to non-diabetic controls. Innovation:This is the first study showing that BET protein inhibition by APA restores angiogenic response in experimental diabetes. Conclusions:Our findings set the stage for preclinical studies and exploratory clinical trials testing APA in diabetic PAD.

International audience; Sphingolipid metabolism is tightly controlled by enzymes to regulate essential processes in human physiology. The central metabolite is ceramide, a pro-apoptotic lipid catabolized by ceramidase enzymes to produce pro-proliferative sphingosine-1phosphate. Alkaline ceramidases are transmembrane enzymes that recently attracted attention for drug development in fatty liver diseases. However, due to their hydrophobic nature, no specific small molecule inhibitors have been reported. Here, we present the discovery and mechanism of action of the first drug-like inhibitors of alkaline ceramidase 3 (ACER3). In particular, we chemically engineered novel fluorescent ceramide substrates enabling screening of large compound libraries and characterized enzyme:inhibitor interactions using mass spectrometry and MD simulations. In addition to reveal a new paradigm for inhibition of lipid metabolising enzymes with nonlipidic small molecules, our data lay the ground for targeting ACER3 in drug discovery efforts.

Introduction: Aquaporin 1 (AQP1) has been implicated in oxidant sensing, but little is known about its differential role in metabolism and function of proliferating (PEC) and senescent (SEC) endothelial cells. We sought to investigate 1) role of AQP1 in modulation of epigenetic modification and senescence-associated secretory phenotype (SASP) in PEC and SEC, and 2) reversal effects of Aqp1 deletion/inhibition on endothelial senescence and dysfunction. Methods: We executed Aqp1 deletion or selective blockade of AQP1 pore (with Bacopaside II 10 μM) to inhibit H 2 O 2 transport in human aortic endothelial cells (PEC p.5 vs SEC p.15 ) and examined its effects on cellular senescence (via SA-β-galactosidase staining) and function (via in vitro angiogenesis and migration assays), and H 2 O 2 -modulated epigenetic modification and SASP (via biochemical assays). Results: We found that AQP1 facilitates physiological H 2 O 2 supply which is necessary for angiogenesis and cell migration in PEC accompanied by marked increase in AMPK T172 phosphorylation and inhibition of acetyl-coA carboxylase (ACC) that provides acetyl-coA for an increased histone 3 (H3) acetylation. Importantly, Aqp1 deletion/inhibition significantly induced senescence and mitochondrial dysfunction in PEC associated with increased SA-β-gal positive cells, upregulated SASP (TNF-α and ICAM-1), and downregulated Idh2. By contrast, decreased AMPK T172 phosphorylation and H3 acetylation accompanied by increased SA-β-gal positive cells, upregulated SASP and mitochondrial dysfunction seen in SEC were reversed by Aqp1 deletion/inhibition. In SEC, we have shown that Aqp1 deletion restores angiogenesis and migration comparable to PEC. Conclusion: We conclude that AQP1 differentially controls metabolism and function in young and senescent ECs via epigenetic and SASP modulation and that AQP1 inhibition represent new possibilities for rejuvenating senescent ECs and treating cardiovascular disease.

Sphingolipid metabolism is tightly controlled by enzymes to regulate essential processes such as energy utilisation and cell proliferation. The central metabolite is ceramide, a pro-apoptotic lipid catabolized by ceramidase enzymes to ultimately produce pro-proliferative sphingosine-1-phosphate. Human ceramidases can be soluble proteins (acid and neutral ceramidase) or integral membrane proteins (alkaline ceramidases). Increasing ceramide levels to increase apoptosis has shown efficacy as a cancer treatment using small molecules inhibiting a soluble ceramidase. Due to the transmembrane nature of alkaline ceramidases, no specific small molecule inhibitors have been reported. Here, we report novel fluorescent substrates (FRETceramides) of ceramidases that can be used to monitor enzyme activity in real-time. We use FRETceramides to discover the first drug-like inhibitors of alkaline ceramidase 3 (ACER3) which are active in cell-based assays. Biophysical characterization of enzyme:inhibitor interactions reveal a new paradigm for inhibition of lipid metabolising enzymes with non-lipidic small molecules.Table of contents summaryUse of synthetic fluorescent ceramide molecules allows the discovery of the first selective drug-like small molecule inhibitors for alkaline ceramidase 3, an intra-membrane enzyme involved in sphingolipid metabolism in health and disease.

Sphingolipids (SLs) are chemically diverse lipids that have important structural and signaling functions within mammalian cells. SLs are commonly defined by the presence of a long-chain base (LCB) that is normally formed by the conjugation of l-serine and palmitoyl-CoA. This pyridoxal 5-phosphate (PLP)-dependent reaction is mediated by the enzyme serine-palmitoyltransferase (SPT). However, SPT can also metabolize other acyl-CoAs, in the range of C(14) to C(18), forming a variety of LCBs that differ by structure and function. Mammalian SPT consists of three core subunits: SPTLC1, SPTLC2, and SPTLC3. Whereas SPTLC1 and SPTLC2 are ubiquitously expressed, SPTLC3 expression is restricted to certain tissues only. The influence of the individual subunits on enzyme activity is not clear. Using cell models deficient in SPTLC1, SPTLC2, and SPTLC3, we investigated the role of each subunit on enzyme activity and the LCB product spectrum. We showed that SPTLC1 is essential for activity, whereas SPTLC2 and SPTLC3 are partly redundant but differ in their enzymatic properties. SPTLC1 in combination with SPTLC2 specifically formed C18, C19, and C20 LCBs while the combination of SPTLC1 and SPTLC3 yielded a broader product spectrum. We identified anteiso-branched-C18 SO (meC18SO) as the primary product of the SPTLC3 reaction. The meC18SO was synthesized from anteiso-methyl-palmitate, in turn synthesized from a precursor metabolite generated in the isoleucine catabolic pathway. The meC18SO is metabolized to ceramides and complex SLs and is a constituent of human low- and high-density lipoproteins.

Sphingolipids (SLs) are structurally diverse lipids that are defined by the presence of a long-chain base (LCB) backbone. Typically, LCBs contain a single Δ4E double bond (DB) (mostly d18:1), whereas the dienic LCB sphingadienine (d18:2) contains a second DB at the Δ14Z position. The enzyme introducing the Δ14Z DB is unknown. We analyzed the LCB plasma profile in a gender-, age-, and BMI-matched subgroup of the CoLaus cohort (n = 658). Sphingadienine levels showed a significant association with gender, being on average ∼30% higher in females. A genome-wide association study (GWAS) revealed variants in the fatty acid desaturase 3 (FADS3) gene to be significantly associated with the plasma d18:2/d18:1 ratio (p = -log 7.9). Metabolic labeling assays, FADS3 overexpression and knockdown approaches, and plasma LCB profiling in FADS3-deficient mice confirmed that FADS3 is a bona fide LCB desaturase and required for the introduction of the Δ14Z double bond. Moreover, we showed that FADS3 is required for the conversion of the atypical cytotoxic 1-deoxysphinganine (1-deoxySA, m18:0) to 1-deoxysphingosine (1-deoxySO, m18:1). HEK293 cells overexpressing FADS3 were more resistant to m18:0 toxicity than WT cells. In summary, using a combination of metabolic profiling and GWAS, we identified FADS3 to be essential for forming Δ14Z DB containing LCBs, such as d18:2 and m18:1. Our results unravel FADS3 as a Δ14Z LCB desaturase, thereby disclosing the last missing enzyme of the SL de novo synthesis pathway.

High-density lipoproteins (HDL) contain hundreds of lipid species and proteins and exert many potentially vasoprotective and antidiabetogenic activities on cells. To resolve structure-function-disease relationships of HDL, we characterized HDL of 51 healthy subjects and 98 patients with diabetes (T2DM), coronary heart disease (CHD), or both for protein and lipid composition, as well as functionality in 5 cell types. The integration of 40 clinical characteristics, 34 nuclear magnetic resonance (NMR) features, 182 proteins, 227 lipid species, and 12 functional read-outs by high-dimensional statistical modeling revealed, first, that CHD and T2DM are associated with different changes of HDL in size distribution, protein and lipid composition, and function. Second, different cellular functions of HDL are weakly correlated with each other and determined by different structural components. Cholesterol efflux capacity (CEC) was no proxy of other functions. Third, 3 potentially novel determinants of HDL function were identified and validated by the use of artificially reconstituted HDL, namely the sphingadienine-based sphingomyelin SM 42:3 and glycosylphosphatidylinositol-phospholipase D1 for the ability of HDL to inhibit starvation-induced apoptosis of human aortic endothelial cells and apolipoprotein F for the ability of HDL to promote maximal respiration of brown adipocytes.

Nitrogen (N) is one of the most important nutrients that plants and microbiota need. In general, under temperate conditions its availability in soil limits biological production especially on intensively cultivated crop fields. Cultivation gradually mitigates organic carbon and nitrogen content of the soil hence a continuous N supply is of crucial importance for reasonable crop production. Therefore, N fertilization is a necessity that has additional environmental effects. Most of the applied fertilizers contain inorganic N, mainly nitrate, which is soluble in water and, accordingly, mobile in the soil. Nitrate can be delivered from the soil by surface runoff or percolation to the deeper layers and the ground water. Present study aimed to compare nitrate losses triggered by the same precipitation event (40 mm h-1) on different slope steepness (5 and 12%) and soil status (seedbed; sealed and crusted condition) on a Cambisol right after inorganic N fertilizer (100 kg ha-1) application using laboratory rainfall simulation. Results indicated that at each precipitation event, only the first 0.5 mm runoff contained considerable amount of nitrate (~170 mg L-1), while main loss was due to percolation (also ~170 mg L1 but all along the percolation period). Accordingly, slope steepness (and also surface conditions) affects nitrate loss via controlling the volume of infiltrated and percolated water. Namely, the crusted steeper slope had the lowest nitrate loss, because most precipitation water was turned to runoff. Evaporation from the soil surface between the precipitations generated upward moisture movement in the profile that finally triggered a higher nitrate concentration on the surface. This N was supposed to be the reason of the increased nitrate content of initial runoff. Accordingly, nitrate loss is inversely proportional to slope steepness, although the effect is subordinate.

Background Sphingolipids are important components of cellular membranes and functionally associated with fundamental processes such as cell differentiation, neuronal signaling, and myelin sheath formation. Defects in the synthesis or degradation of sphingolipids leads to various neurological pathologies; however, the entire spectrum of sphingolipid metabolism disorders remains elusive. Methods A combined approach of genomics and lipidomics was applied to identify and characterize a human sphingolipid metabolism disorder. Results By whole-exome sequencing in a patient with a multisystem neurological disorder of both the central and peripheral nervous systems, we identified a homozygous p.Ala280Val variant in DEGS1, which catalyzes the last step in the ceramide synthesis pathway. The blood sphingolipid profile in the patient showed a significant increase in dihydro sphingolipid species that was further recapitulated in patient-derived fibroblasts, in CRISPR/Cas9-derived DEGS1-knockout cells, and by pharmacological inhibition of DEGS1. The enzymatic activity in patient fibroblasts was reduced by 80% compared with wild-type cells, which was in line with a reduced expression of mutant DEGS1 protein. Moreover, an atypical and potentially neurotoxic sphingosine isomer was identified in patient plasma and in cells expressing mutant DEGS1. Conclusion We report DEGS1 dysfunction as the cause of a sphingolipid disorder with hypomyelination and degeneration of both the central and peripheral nervous systems. Trial registration Not applicable. Funding Seventh Framework Program of the European Commission, Swiss National Foundation, Rare Disease Initiative Zurich.

Sepsis caused by LPS is characterized by an intense systemic inflammatory response affecting the lungs, causing acute lung injury (ALI). Dysfunction of mitochondria and the role of reactive oxygen (ROS) and nitrogen species produced by mitochondria have already been proposed in the pathogenesis of sepsis; however, the exact molecular mechanism is poorly understood. Oxidative stress induces cyclophilin D (CypD)-dependent mitochondrial permeability transition (mPT), leading to organ failure in sepsis. In previous studies mPT was inhibited by cyclosporine A which, beside CypD, inhibits cyclophilin A, B, C and calcineurin, regulating cell death and inflammatory pathways. The immunomodulatory side effects of cyclosporine A make it unfavorable in inflammatory model systems. To avoid these uncertainties in the molecular mechanism, we studied endotoxemia-induced ALI in CypD−/− mice providing unambiguous data for the pathological role of CypD-dependent mPT in ALI. Our key finding is that the loss of this essential protein improves survival rate and it can intensely ameliorate endotoxin-induced lung injury through attenuated proinflammatory cytokine release, down-regulation of redox sensitive cellular pathways such as MAPKs, Akt, and NF-κB and reducing the production of ROS. Functional inhibition of NF-κB was confirmed by decreased expression of NF-κB-mediated proinflammatory genes. We demonstrated that impaired mPT due to the lack of CypD reduces the severity of endotoxemia-induced lung injury suggesting that CypD specific inhibitors might have a great therapeutic potential in sepsis-induced organ failure. Our data highlight a previously unknown regulatory function of mitochondria during inflammatory response.

Sphingolipids including ceramides are important components of cellular membranes and functionally associated with fundamental processes such as cell differentiation, neuronal signaling and myelin sheath formation. Defects in the synthesis or degradation of sphingolipids are associated with various neurological pathologies, however, the entire spectrum of disorders affecting sphingolipid metabolism remains elusive. By whole-exome sequencing in a patient with a multisystem neurological disorder of both the central and peripheral nervous system, we identified a homozygous variant p.(Ala280Val) inDEGS1,encoding an enzyme of the ceramide synthesis pathway. The blood sphingolipid profile and patient-derived fibroblasts both showed a significant shift from the unsaturated to the dihydro-forms of sphingolipids. Moreover, an atypical and potentially toxic sphingolipid metabolite is formed as consequence of the altered synthesis pathway. The changes in the sphingolipid profile were recapitulated in a CRISPR/Cas-basedDEGS1knockout HAP1-cell model and by chemical inhibition of DEGS1, suggesting a loss of DEGS1 function in the disease. DEGS1 insufficiency is thus a novel cause for a multisystem neurological disorder. A sphingolipid-rich diet may correct the metabolic profile and improve the clinical outcome of affected individuals and suggests that this heritable condition might be treatable.AbbreviationsSLSphingolipidsSPTserine-palmitoyltransferaseCerCeramidesdhCerdihydroceramideS1Psphingosine-1-phosphateSOsphingosineHSANhereditary sensory and autonomic neuropathy

AIM: Chronic idiopathic axonal polyneuropathy (CIAP) is a slowly progressive, predominantly sensory, axonal polyneuropathy, with no aetiology being identified despite extensive investigations. We studied the potential role of the metabolic syndrome, neurotoxic 1-deoxysphingolipids (1-deoxySLs), microangiopathy and inflammation in sural nerve biopsies. METHODS: We included 30 CIAP-patients, 28 with diabetic distal symmetrical polyneuropathy (DSPN) and 31 healthy controls. We assessed standardised scales, tested for the metabolic syndrome, measured 1-deoxySLs in plasma, performed electroneurography and studied 17 sural nerve biopsies (10 CIAP; 7 DSPN). RESULTS: One third of the CIAP-patients had a metabolic syndrome, significantly less frequent than DSPN-patients (89%). Although the metabolic syndrome was not significantly more prevalent in CIAP compared to healthy controls, hypercholesterolemia did occur significantly more frequent. 1-deoxySLs were significantly and equally elevated in both patient groups compared to healthy controls. Mean basal lamina thickness of small endoneurial vessels and the number of CD68- or CD8-positive cells in biopsies of CIAP- and DSPN-patients did not differ significantly. However, the number of leucocyte-common-antigen positive cells was significantly increased in CIAP. CONCLUSIONS: A non-significant trend towards a higher occurrence of the metabolic syndrome in CIAP-patients compared to healthy controls was found. 1-deoxySLs were significantly increased in plasma of CIAP-patients. Microangiopathy and an inflammatory component were present in CIAP-biopsies. ispartof: PLoS One vol:12 issue:1 ispartof: location:United States status: published